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Developing my universe more and I've been considering a lot for it. One of these is diseases from other planets with life. Organisms of any size vary greatly in this universe.

Some of these extraterrestrials I've thought of would typically send machines or drones to visit planets, but sometimes they may land physically. One race, a small rat-like species, spread out to different planets because they rendered their homeplanet uninhabitable due to nuclear war.

I would have to consider that these creatures could die of disease once landing, but then it can also be the other way around, and they spread diseases to the natives.

I suppose it may depend on the life and how the organisms enter a body. One thing I've thought of is that most, if not none of the diseases could infect any extraterrestrial. Their proteins are built differently, and because they are not familiar with their structure, they would be unable to attach.

I'm unsure if this is plausible, but it sounds like it to me and I came here for reassurance nor possibly other answers. I would've spent more time researching microscopic creatures and proteins, though I've been busy and I do want to get a relatively quick answer.

Thank you!

Averian
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  • Diseases are very specific to their hosts. Most animal diseases are harmless to humans, and vice versa. I suppose your aliens are more distant from us biologically that our rats, so everyone must be safe (until microorganisms mutate). – Alexander May 14 '18 at 21:20

4 Answers4

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If two planets' life forms evolved separately, diseases from one planet could probably not infect higher lifeforms from another planet, except that there could be rare exceptions when that was possible due to by coincidence two planets evolving very similar lifeforms.

For example, diseases from planet A might only be able to infect lifeforms from one planet out of every thousand that had higher lifeforms, or diseases from planet B might only be able to infect higher lifeforms from one planet out of a million that had higher lifeforms.

Except for extremely rare cases of two planets evolving very similar lifeforms, interplanetary and interstellar infections should only be plausible in stories set in fictional universes where the lifeforms on different planets are related due to natural or deliberate panspermia.

https://en.wikipedia.org/wiki/Panspermia1

M. A. Golding
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Disease passing between humans and extraterrestrial species is impossible. (Unless you want to handwave the impossibility and make it so, which is your prerogative as a writer.) Our organisms are just too different.

Think of it this way: is it possible for the same disease to affect a human and a shrimp? A human and an oak tree? Yet the tree, the shrimp and the human all share a common forefather, we share parts of our cell structure, we share some bits of DNA. We share the very fact that we have cells and DNA. We share nothing of this with extraterrestrials, since they would have evolved completely separately. There are no commonalities whatsoever that could potentially be attacked. In fact, we'd share more commonalities with the germ attacking us than with the alien visiting us.

The only way to get around this is if you assume the species on different planets did not evolve separately and independently, but had a common ancestor. Even then, the ancestor would have to be pretty close - closer to us than the oak tree and the shrimp. And even then, that's unlikely. Germs, viruses and other parasites evolve alongside their hosts, aiming live off them. What species of parasite could reasonably evolve to live off us, as well as some species light-years away?

Galastel supports GoFundMonica
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Everyone read War of the Worlds and Andromeda Strain so listen to the planetary protection officer.

Most of first contact is proving exactly how biologically dangerous we are to eachother. Only those that are mutually sterile are allowed on the planet. This could allow a mistake of not testing a third party's microbe to be a problem for the rat-people being present on Earth if it doesn't effect our kind of life.

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The others are mostly right. An organism that develops on another planet should not be able to infect us the same way a Earth organism would.

But, there is an exception if you want to use it; the human body is essentially a warm bag of slightly salty water and minerals. An alien organism could decide to just use the raw water and minerals, and not bother with the whole infection highjack the cells and reproduce thing, and if that happened our immune systems might have a really hard time detecting and eliminating the threat.

AndyD273
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